Regulatory Matters (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014	Dec. 31, 2013
Storm Damage Provision	$ 2.6
Deferred Storm Costs [Member]
Storm Damage Provision	22.3	25.6
DP&L [Member]
Storm Damage Provision	2.6
DP&L [Member] \| Deferred Storm Costs [Member]
Storm Damage Provision	$ 22.3	$ 25.6

A noncash adjustment to the provision established for storm damage by an oil, gas, or utility company.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Name:	us-gaap_StormDamageProvision
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration